Thats it.
At the official U.S. Supreme Court website. Look at the bottom of this page.
You can also visit Oyez. No transcripts per se, but you can hear the actual arguments.
Robin
You may find transcripts of arguements in open court sessions, but you will not find anything about the discussions and decision making processes among the justices themselves, except through personal papers published by the justices themselves.
You might check Audible .
Look under the ‘free audio’ section.